摘要:
Example methods, apparatus and articles of manufacture to calibrate valve-mounted instruments, such as a position controllers and/or a position transmitter, are described. An example tangible computer-readable medium comprises instructions that, when executed, cause a machine to receive a first value representative of a current position of a valve, receive a second value representative of a sensitivity of a position sensor, compute a first estimated value corresponding to an expected fully-open position of the valve based on the received first and second values, compute a second estimated value corresponding to an expected fully-closed position of the valve based on the received first and second values, receive a control signal representative of a desired position of the valve, and in response to the received control signal, position the valve at substantially the desired position based on the first and second estimated values.
摘要:
An intrinsically safe redundant regulator circuit includes a plurality of voltage limiting regulators between a regulated rail and a ground rail. Each of the plurality of voltage limiting regulators includes: (i) a shunt regulator component configured to clamp a voltage across the regulated rail and the ground rail to a safety clamp voltage value; and (ii) one or more components, where a property of each of the one or more components is selected to configure the safety clamp voltage value.
摘要:
A control signal protection device having a first operational mode and a second operational mode includes a first terminal pair that connects the signal protection device to a control system and a second terminal pair that connects the converter to a field device. The control system provided a control signal to the control system protection device. The control signal device further includes a power storing element for temporary accumulation of electric energy and a switching circuit for controlling operational mode of the signal protection device. Electric energy is stored in the power storing element in the first operational mode. Electric energy stored in the power storing element is supplied to a positive terminal in the second terminal pair in the second operational mode.
摘要:
Example methods, apparatus and articles of manufacture to calibrate valve-mounted instruments, such as a position controllers and/or a position transmitter, are described. An example method disclosed herein includes securing a position of a flow control member of a control valve assembly to prevent movement of the flow control member and installing a controller to the control valve assembly. The method includes activating a user interface of the controller after the controller is coupled to the control valve assembly, entering a position sensor sensitivity value and a single-point position value, the single-point position value being representative of the secured position of the flow control member, applying a single-point calibration value, placing the controller in a control mode, and releasing the position of the flow control member, the controller to self-calibrate during operation of the control valve assembly based on the position sensor sensitivity value and the single-point position value while the control valve assembly is in operation.
摘要:
A system and method using a valve controller to control a valve. The valve controller including a position controller for moving the valve and a transmitter for providing information about the position of the valve. A calibration table and/or chart based on calibration data of the position controller is generated to provide a transmitter output value, wherein the transmitter need not be separately calibrated. The calibration table and/or chart may be stored in the position controller and provided to the transmitter upon completion of the calibration of the position controller. Dual power supply circuitry may be configured wherein a first power source supplies power to both the position controller and the transmitter to facilitate automatic calibration of the transmitter even when only the position controller is powered.
摘要:
An intrinsically safe redundant regulator circuit includes a plurality of voltage limiting regulators between a regulated rail and a ground rail. Each of the plurality of voltage limiting regulators includes: (i) a shunt regulator component configured to clamp a voltage across the regulated rail and the ground rail to a safety clamp voltage value; and (ii) one or more components, where a property of each of the one or more components is selected to configure the safety clamp voltage value.
摘要:
An intrinsically safe voltage clamping device includes a regulated rail, a ground rail, and a shunt regulator assembly. The shunt regulator assembly is coupled to both the regulated rail and the ground rail and includes one or more regulating components. The shunt regulator assembly is configured to clamp a voltage applied across the regulated rail and the ground rail to a safety clamp voltage value. The intrinsically safe voltage clamping device also includes a power-sensing component configured to cause one or more limiting components to reduce a power dissipated in the respective regulating components without raising the clamp voltage.
摘要:
An intrinsically safe redundant regulator circuit includes a plurality of voltage limiting regulators between a regulated rail and a ground rail. Each of the plurality of voltage limiting regulators includes: (i) a shunt regulator component configured to clamp a voltage across the regulated rail and the ground rail to a safety clamp voltage value; and (ii) one or more components, where a property of each of the one or more components is selected to configure the safety clamp voltage value.
摘要:
A diagnostic system and method for a field device implemented in a safety instrumented system includes detecting an occurrence of a safety event associated with the field device, overriding normal control of the field device to cause the field device to enter a safe state in response to the detected occurrence of the safety event, verifying the override of normal control of the field device, and transmitting a control signal to cause the field device to enter the safe state.
摘要:
A control signal protection device having a first operational mode and a second operational mode includes a first terminal pair that connects the signal protection device to a control system and a second terminal pair that connects the converter to a field device. The control system provided a control signal to the control system protection device. The control signal device further includes a power storing element for temporary accumulation of electric energy and a switching circuit for controlling operational mode of the signal protection device. Electric energy is stored in the power storing element in the first operational mode. Electric energy stored in the power storing element is supplied to a positive terminal in the second terminal pair in the second operational mode.